ATxmega256A3BU Atmel Corporation, ATxmega256A3BU Datasheet - Page 224

• Manufacturer Part Number: ATxmega256A3BU
• Manufacturer: Atmel Corporation

Specifications of ATxmega256A3BU

• Flash (kbytes): 256 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 47
• Ext Interrupts: 49
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 8
• Twi (i2c): 2
• Uart: 6
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 16
• Adc Resolution (bits): 12
• Adc Speed (ksps): 2000
• Analog Comparators: 4
• Resistive Touch Screen: No
• Dac Channels: 2
• Dac Resolution (bits): 12
• Temp. Sensor: Yes
• Crypto Engine: AES/DES
• Sram (kbytes): 16
• Eeprom (bytes): 4096
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: Yes
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.6 to 3.6
• Operating Voltage (vcc): 1.6 to 3.6
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 7
• Output Compare Channels: 22
• Input Capture Channels: 22
• Pwm Channels: 22
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

19.2.2
19.2.3
19.2.4
8331A–AVR–07/11
Clock Domains
Power Domains
Interrupts and Events
The RTC32 is asynchronous, operating from a different clock source, and the counter is inde-
pendent of the main system clock and its derivative clocks, such as the peripheral clock. For
control and count register updates, it will take a number of RTC32 clocks and/or peripheral clock
cycles before an updated register value is available in the register or until a configuration change
has effect on the RTC. This synchronization time is described for each register.
The Peripheral clock must be more than eight times faster than the RTC32 clock (1.024kHz or
1Hz) when any of the Control or the Count register are accessed (read or written), more than 12
times faster when the Count register is written.
For devices where the RTC32 is located in the V
enables the RTC32 to also function with no main V
to automatically switch from the V
voltage level for the device. When the V
switched back to V
The RTC32 can generate both interrupts and events. The RTC32 will give a compare interrupt
request and/or event at the next count after the counter value equals the compare register value.
The RTC32 will give an overflow interrupt request and/or event at the next count after the coun-
ter value equals the period register value. The overflow will also reset the counter value to zero.
Due to the asynchronous clock domains, events will be generated only for every third overflow or
compare match if the period register is zero. If the period register is one, events will be gener-
ated only for every second overflow or compare match. When the period register is equal to or
above two, events will trigger at every overflow or compare match, just as the interrupt request.
CC
.
CC
domain to the V
CC
voltage is restored, the power is automatically
BAT
CC
Atmel AVR XMEGA AU
BAT
power domain, the battery backup feature
available. A dynamic power switch is used
domain if V
CC
falls below the operating
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